Currently, refractory metals and their nitrided compounds, such as TaN and TiN, are employed as metal barrier layers against copper (Cu) penetration into silicon oxide (SiO2) and low-k dielectric materials (where a low-k dielectric material has a dielectric constant (k) of less than about 3.0). However, beyond 0.1 μm, the main advantage of using low-resistance copper interconnects will be further negated by such high-resistance metal barrier layers resulting in the great increase of total RC (resistance capacitance) time delay.
Moreover, with continually thinning, these metal barrier layers will have reliability concerns such as line-line leakage, time dependent dielectric breakdown (TDDB) lifetime and bias-temperature stress (BTS) due to their poor barrier integrity.
U.S. Pat. No. 6,358,842 B1 to Zhou et al. describes a dual damascene process.
U.S. Pat. No. 6,352,917 B1 to Gupta et al. describes a reverse dual damascene process.
U.S. Pat. No. 6,326,079 B1 to Philippe et al. describes an SiOC barrier layer.
U.S. Pat. No. 6,265,321 B1 to Chooi et al. describes an air bridge process for interconnects.